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Note: The evaporation forecast map is currently in beta and may undergo further changes.

Forecast of Total May–July 2018 Reservoir Evaporation

The Texas Water Development Board is providing experimental forecasts
of May‒July reservoir evaporation using a similar statistical forecast
technique to that which it used for the generation of
May‒July rainfall forecasts.

These forecasts are being issued from January through end-April.
The forecasts are updated every two weeks.

The forecasts from January through March are based on predicted values of
April atmospheric circulation patterns and soil moisture over Texas known
to influence May‒July rainfall and, by assumption, reservoir evaporation
over the same period. The predictions are obtained from the Climate
Forecast System version 2 (CFSv2,
Saha et al., 2014), which is the operational dynamical seasonal
forecast model of the National Oceanic and Atmospheric
Administration-National Centers for Environmental Prediction.

The forecast issued at the beginning of May is based on observed
atmospheric circulation patterns and soil moisture over Texas known
to influence May‒July rainfall and, by assumption, reservoir evaporation.
Observations of April atmospheric circulation patterns and soil moisture
over Texas are obtained from the Climate Forecast System Reanalysis
dataset (
Saha et al., 2010).

The forecast maps provide deterministic forecasts (i.e. quantitative estimates)
of cumulative reservoir evaporation over the May‒July season over each major
reservoir (i.e. reservoirs with capacity greater than 5000 acre-feet) in Texas.
Hovering over a reservoir opens up a popup, which provides the reservoir evaporation
value over the selected reservoir.

Disclaimer

The May‒July seasonal reservoir evaporation forecast is an experimental forecast. It is primarily meant to be an information source to aid the implementation of drought contingency and emergency management plans. The TWDB provides information via this web site as a public service. Neither the State of Texas nor the TWDB assumes any legal liability or responsibility or makes any guarantees or warranties as to the accuracy, completeness, or suitability of the information for any particular purpose.

Acknowledgements

The provision of these rainfall and reservoir evaporation forecasts via this website was made possible through the U.S. Bureau of Reclamation WaterSMART Drought Resiliency funding to the Texas Water Development Board (Grant: R15AP00184; Fiscal Year: 2015).